Automatic repeating relay



June 30, 1959 Filed Sept. 2'7, 1956 UTILIZATION CIRCUIT FIG. 2

5 E34 E] j INVENTOR,

CARL ORLANDO.

2M; 91 QIMW ATTOR/VEX ited States Patent 2,892,954 AUTOMATIC REPEATIN G RELAY Carl Orlando, Long Branch, N.J., assig'nor to the United States of America as represented by the Secretary of the Army Application September 27, 1956, Serial No. 612,566

4 Claims. (Cl. 307-132) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government, for governmental purposes, without the payment of any royalty thereon.

This invention relates to relay devices which function automatically to repeat their operating cycle at measured time intervals and particularly to such devices in which the repetition rate is closely regulated.

The invention fulfills a need for an efficient, rugged and precisely functioning interval measuring device. High precision and consistent reliability is maintained by the device throughout a long period of use. Thermionic tubes or like devices having delicate parts and relatively complicated circuitry are not used. Moreover, the device of the invention is capable of controlling high level elec-- tric currents with low level losses, and also of operating mechanical timing devices.

The invention may be briefly described as follows: An electromagnetically actuated arm or armature is pivoted at some point along its length and is vibrated upon its pivot by the action of electromagnets. Movement of the armature opens and closes one or more contacts, thereby acting to control the flow of current in an external circuit, or as will be pointed out hereinafter the movement of the armature may be utilized for other purposes.

Two electromagnets acting upon the armature supply the motive power. One of the magnets is the main operating magnet and the other acts as a timing correction de vice. Both magnets are energized at the same instant. Resistance and capacity timing circuits act in conjunction with an energy source such as a battery to energize the magnets which in turn actuate the armature at regular intervals. I

The second electromagnet acts in opposition to and has less power than the main magnet. During each cycle of operation the second magnet presents a mechanical force in opposition to the force of the main magnet. This difference in force establishes a resultant pull upon the armature. This pull remains constant despite changes of voltage from the battery. Since the pull on the armature is always constant and the elements of the resistance capacity circuits have constant characteristics, the timing cycle andtherefore the frequency of operation of the device remains constant. The function of the compensating device will be pointed out in more detail hereinafter.

It is a primary, object ofv the invention to provide an automatic relay having a constant repetition rate.

A further object of the invention is to provide an automatic relay ofrugged construction having high efficiency and a minimum of component parts.

A further object of the-invention is to provide an apparatus for controlling a load for measured periods and 2,892,954 Patented June 30, 1959 2 ting the controlling device to function independently of capacitance and inductance characteristics which may be present in the load.

A further object of the invention is to provide an apparatus of the character indicated containing no thermionic devices such as tubes, transistors, or rectifiers, thereby avoiding the fragile nature of such devices and also the complication and power limitations thereof.

A further object of the invention is to provide an automatic pulsing device capable of controlling high current loads without employing amplifying devices.

Other objects and features of the invention will more fully appear from the following description and will be particularly pointed out in the claims.

. To provide a better understanding of the invention, a particular embodiment thereof will be described and illustrated in the accompanying drawings in which Fig. 1 illustrates diagrammatically a particular embodiment of the invention and Fig. 2 is a detail view showing a difierentmeans for mechanically biasing the relay armature.

The component parts and their arrangement as shown in the drawings represent one example of a wide variety of arrangements embraced by the broad scope of the invention. In the embodiment shown, the invention assumes the general arrangement which includes a special form of magnetically operated relay having an armature 5 pivoted at 6. The armature, or at least a portion thereof, is made of magnetic material to be attracted by magnetic fields created by the electromagnets 7 and 8 which are desirably provided with magnetically permeable cores situated adjacent the armature. In the specific form shown the magnets act on opposite sides of one leg 9 of the armature although other arrangements may be made. The magnet 7 is the main operating magnet and has substantially greater pulling power than magnet 8. The magnets when energized exert a rotative force upon the armature which moves about its pivot 6, the magnitude of the force being proportional to the difference in force exerted by the respective magnets.

. The leg 9 of the armature has a contactor bar 10 thereon which coacts with a pair of contacts 11 secured in fixed position. The switch thus formed acts to open and close circuits connecting the windings of magnets 7 and 8 to a suitable source of energy such as battery 12. The other leg 13 of the armature is supplied with suitable contacts 14 which engage a contactor bar secured to and insulated regulated time intervals wherein high power levels may be i from the arm 13 of the armature. The contacts 14 act to open and close an external utilization circuit .15 which is electrically isolated from the relay circuits. The contacts 14 may be of any construction to suitably open and close a circuit or the mechanical motion of the armature may be used for purposes other than controlling an electric circuit. The load may be any device which must be intermittently operated, such as an aerial camera while making a topographic survey.

Means are also provided for measuring the duration of the'on and off periods in the operating cycle of the device. Such means may be conventional resistance and capacity timing circuits used in connection with the windings 7 and 8. The main winding 7 is connected at one end to the battery 12 by the lead wire 16, which is also connected to one end of the winding 8. The other ends of the Windings 7 and 8 are connected respectively to contacts 11. Completion of the circuits to the battery is made through the leg 9 of the armature and the lead 17, which may have a flexible portion 18 to permit free mechanical movement of the armature and also provide good electrical continuity in the circuit.

The winding 7 is shunted by a condenser 19 and a variable resistance 20, while the coil 8 is shunted by a condenser 21. The connection from the coil 7 to one of the contacts 11 is provided with a current limiting resistor 22, and the lead wire 16 where it is connected to the coil 8 is provided with a current limiting resistor 23.

The capacity of the shunting condensers 19 and 21 and the inductance of the coils are so calculated in connection with the voltage of the battery 12 that a desired time interval will elapse after battery current starts to flow and before the magnets have acquired the critical pulling power necessary to break their connection with the bat tery by actuating the armature.

The armature is mechanically biased to close the contacts 11 when no current or low current is flowing in the coils. The biasing force may be created by a spring as shown in Fig. 2 of the drawings, or by a permanent magnet 24 situated adjacent to the armature. A suitable switch 25 may be provided to start and stop operation of the device.

, The respective inductances of the coils 7 and 8 are calculated to provide a compensating factor which automatically stabilizes the timing cycle of the device if and when a shift in voltage occurs in the source of energy. It is required that the stabilizing means be accurately effective throughout a somewhat limited range, for example, 10 percent of the normal operating voltage.

One of the electromagnets, namely the operating magnet 7, must have greater pulling power upon the armature than the compensating magnet 8 when the same voltage is applied to each one. Also, to insure consistent timing of the relay despite shifts in applied voltage, the rate of change of flux in each magnet must be the same for a given rate of change in applied voltage. When this requirement is satisfied, the difference in pull between the magnets remains a fixed quantity and therefore the armature will be actuated at the end of a fixed measured time interval after the voltage is applied to the magnet.

The well known principles of electromagnetic design provide the means to create the required characteristics in the electromagnets. Inasmuch as the results need to be obtained only for the static condition when the armature is in position for closing the circuits to the magnets, the problem of properly determining the correct values is simplified. The required result may be obtained by suitably adjusting the ohmic resistance of the magnet windings in such a manner that the change in voltage upon the smaller magnet 8 will increase the magnetic flux therein to a value, which will react upon the change of flux which takes place in the magnet 7 when a voltage shift occurs, in such a manner that the changes in pull of the magnets due to voltage change are cancelled out.

In operation, at the instant the switch 25 is closed the current flows to the timing circuits and magnetic flux is built up in the magnets 7 and 8 until the ditference in pull exerted by the magnets overcomes the pull of the permanent magnet 24. This condition of the system will hereinafter be termed the critical armature actuating condition. Such condition will occur at the end of a specified time interval and at a predetermined voltage determined by the charge on the condensers. This voltage desirably is somewhat lower than the battery voltage. The time interval will remain fixed even though the applied voltage may shift a slight amount. This is true because the time constant of the circuit is established largely by the values of resistance capacity and inductance of the circuits. In the device of the invention these values remain constant except when one or more of the values may purposely be changed to obtain a new time interval as by adjustment of the resistor 20. When the armature moves to open the circuit at the contacts 11, the contacts 14 close to produce a predetermined required elfect in the external circuit connected to the device.

At this instant, the contacts 11 are held open by reason of the firm action of the armature which has moved close to the maximum density of the flux in the magnet 7. At this time also the voltage of the inductance rises which boosts the condenser voltage. It will be seen, therefore, that there will again be established a time lapse while the enengy in the circuit dissipates through the resistor 20 and the coils on the magnets. This period ends when the pull of the magnet 7 returns to the point where the permanent magnet 24 again acts to move the contacts 11 into engagement with their coacting contactor bar, at which time the cycle above described is repeated.

In the device of the present invention, without the compensating magnet 8, a change in timing of its operating cycle would take place in the event of an increase or decrease in applied voltage. Such change in voltage would shift the instant at which the armature is pulled away from the permanent magnet. With the coil 8 in operation, compensation for the change in pull of magnet 7 due to the voltage shift takes place. The magnet 8 causes the armature to move at the same critical armature operating condition as existed before the voltage changed. It will thus be seen that automatic regulation of the timing cycle and the repetition rate is achieved.

What is claimed is:

1. An automatic repeating relay comprising a magnetically operated armature, a switch operated by said armature, a biasing means normally acting to close said switch, a main electromagnet acting upon said armature to open said switch, a compensating electromagnet connected in parallel with, of less power than and acting in opposition to said first magnet, separate external resistance and capacity timing circuits connected to said magnets, a source of electric energy connected through separate contacts on saidswitch respectively to each of said electromagnets, whereby when the magnets are energized the switch will open at the instant when the pull exerted by said main magnet overcomes the force of said biasing means, thus the balance of pull exerted by said magnets will be held constant independent of voltage shift in said energy source and an external device connected to and timed by the movement of said armature.

2. A repeating relay according to claim 1 and wherein the values of the timing circuits are manually adjustable to vary the time cycle of the relay.

3. A repeating relay according to claim 1 and wherein the voltage of the energy source is greater than the actuating voltage of the relay.

4. An automatic repeating relay comprising an armature at least a portion of which is of magnetic material, a switch actuated by said armature, a pair of electromagnets of unequal power connected in parallel and acting in opposition upon said armature, a source of electric energy connected to both of said magnets by the closing action of said switch, a biasing means having less power than the difference between the forces produced by said magnets, said biasing means acting normally to close said switch, said electromagnets being designed to produce an equal flux change in said magnets upon a shift in applied voltage, separate external resistance and capacity timing circuits connected to said electromagnets and an external device controllable by movement of said armature.

References Cited in the file of this patent UNITED STATES PATENTS 1,748,862 Brown Feb. 25, 1930 2,208,125 Feingold July 16, 1940 2,394,294 Giuseppe Feb. 5, 1946 2,437,756 Rosing Mar. 16, 1948 FOREIGN PATENTS 847,227 France June 26, 1939 

